Rolling mills

ABSTRACT

A rolling mill stand having at least one hydraulic piston and cylinder assembly for controlling the roll gap has provision for sensing continuously the relative positions of the movable and the fixed components of the piston and cylinder assembly. The sensing means comprise two position sensing devices spaced at different distances from, but on the same side of, the assembly. From a consideration of the output signals from the two devices, the displacement of the movable component of the piston and cylinder assembly relative to the fixed component can be determined, and this determined value takes into account any tilting of the piston of the assembly which may occur.

i United States Patent Hargreaves Nov. 4, 1975 ROLLING MILLS 75 [me t Thom Walt H Primary ExaminerMilton S. Mehr 1 n or sheffizlsd g g Attorney, Agent, or Firm-Danie] Patch; Henry C. [73] Westin Assignee: Davy-Loewy Limited, Sheffield, England [22] Filed: Feb. 13, 1975 [21] Appl. No.: 549,577

[30] Foreign Application Priority Data Feb. 22, 1974 United Kingdom 8198/74 [52] US. Cl. 72/31; 33/182; 72/21 [51] Int. Cl. B21B 37/08 [58] Field of Search 72/21, 35, 32, 31

[56] References Cited UNITED STATES PATENTS 3,850,015 11/1974 Andresen 72/31 3,861,183 1/1975 Fukui et a1 72/21 [57] ABSTRACT A rolling mill stand having at least one hydraulic piston and cylinder assembly for controlling the roll gap has provision for sensing continuously the relative positions of the movable and the fixed components of the piston and cylinder assembly.

The sensing means comprise two position sensing devices spaced'at different distances from, but on the same side of, the assembly. From a consideration of the output signals from the two devices, the displacement of the movable component of the piston and cylinder assembly relative to the fixed component can be determined, and this determined value takes into account any tilting of the piston of the assembly which may occur.

4 Claims, 3 Drawing Figures US. Patent Nov. 4, 1975 3,916,661'

7 l 'ROLLING'MILLS This invention relates to rolling mills and is particu-' larly concerned with a rolling mill'standhaving at least one hydraulic'piston-and cylinder assembly for controlling the roll gap. In'such a stand, aseparate piston and cylinder assembly is usually arranged in the mill housing at the bottom of each window, with the moving part of each assembly engaging against thebearing chock assemblies at the ends of the lowermost roll. Usually; the cylinders of the assemblies are formed in or secured to the housing and the pistons form themoving'part of the assembly; however, the opposite is possible, the cylinders moving on'the pistons which are secured'to the housing. 1

For the proper control of the roll gap, it is advantageous to sense continuously the relative" positions of the components of the or each piston and cylinder assembly. Because the moving component of'the assembly is liable to tilt relative to the fixed component, the posi tion measurement should be effected at the axis of the assembly. But, location 'of a position sensor within the cylinder and on its axis, while'being the-ideal solution, is prohibited by the inaccessibility of the sensor, it being necessary to remove the roll stack and the moving part of the component, before the sensor may be serviced.

It has therefore been proposed to use two position sensors in relation to each piston and cylinder assembly, with the sensors disposed on a radial line through the assembly axis, but on opposite sides of that axis; the sensors acting between a fixed part of the stand and a part which moves with the moving component of the assembly. That arrangement has the advantage that both sensors are more accessible than in the ideal solution, in that removal of the roll stack is no longer necessary. if the sensors are arranged, one at the front the other at the rear of the stand, at least the former is readily accessible and in a reasonable environment. The rear sensor, however, is now located beneath the mill rolls in an area contaminated with roll coolants and other deleterious materials. The arrangement is therefore practical, but disadvantageous.

According to the present invention a rolling mill stand having at least one piston and cylinder assembly for adjusting the gap between the rolls of the mill and means for determining the displacement of the central part of the movable member of the assembly relative to the fixed part of the assembly, said means including two position sensing devices spaced at different distances from, but on the same side of, the assembly.

By virtue of the invention, it is possible to have both of the sensors associated with an assembly at the front of the mill, rendering the sensors accessible for servicing and at least partly protected from contaminants.

The position sensing devices associated with each assembly are preferably arranged on a common radial line through the axis of the assembly, and may be arranged between a fixed part of the mill and a part which moves with the moving component of the assembly, such as a bearing chock assembly against which the moving component of the assembly acts.

The invention will be more readily understood from the following description of a sensing arrangement for 2 FIG. 1 illustrates diagrammatically a piston and cylinder assembly for a hydraulic mill,

FIG. 2 shows the geometry of that arrangement, and FIG. 3 is a view of part of a mill showing a piston-cylinder assembly and two position sensors.

In FIG. 1 the piston and cylinder assembly is represented by a cylinder 12 in which is slidably arranged a piston 13. The cylinder 12 is secured to the housing of the mill, while the piston 13 engages against the underside of a bearing chock assembly of the roll of the stack, e.g. one of the chocks of the lower back-up roll in a four-high mill. For the control of the roll gap, it is necessary to monitor. continuously the position of the piston 13 relative to the cylinder 12 and, because the piston can tilt, as exemplified in FIG; 1, the measurement should be performed at the axis 14 of the assembly. For example, the distance X between the centre of the top surface of the piston 13 and afixed'point on the axis of the cylinder 12 should be continuously measured.

In FIG. 1, A and B represent two position sensors which are arranged on a diameter of the cylinder and at the same distance from, but on opposite sides of, the axis 14. Each sensor A, B continuously measures the separation between the'cylinder 12 and surface of the chock immediately above it. By takingthe mean of the readings of the two sensors, a value for the distance X may be determined. I

As explained above, the arrangement of the sensors A, B on opposite sides of the axis 14 is not altogether satisfactory. Instead, two sensors B, C may be provided, again on the same cylinder diameter, but on the same side of, and at different distances from, the axis 14. Once again, the sensors B, C are fixed relative to the cylinder 12 and measure the separations of the chock immediately above the sensors from, for example, the horizontal median plane 15 through the cylinder 12. From the values e e for the separations given by the sensors B, C, the distance X on the axis of the assembly may be derived as will be explained later.

In FIG. 2, the axis of the piston and cylinder assembly is again indicated at 14, X representing the same distance as in FIG. 1 R1, R2 are the radial distances of the sensors B, C respectively from axis 14, while e e are again the readings given by the sensors B and C. The

In practice, the signals from the two sensors B, C which represent the values e,, e respectively, are fed into a simple calculating circuit together with the constant factors R1, R2, the circuit operating to perform in accordance with the equation given above, in order to give an output representing the required value X.

Referring now to FIG. 3, the bottom roll 20 of a rolling mill stand is supported at its ends in bearing chock assemblies one of which is indicated byreference numeral 22. The chock assemblies are located in windows 24 provided in the mill housings 26. A hydraulically actuatable piston and cylinder assembly comprising a cylinder 28 and a piston 30 is located in each window with the cylinder fixed to the housing and the piston engaging the underside of the bearing chock immediately above it. In use, the bearing chock assemblies may tilt relative to the mill housings and the piston and cylinder assemblies are constructed to allow the piston to tilt relative to the cylinders.

A bracket 32 is secured to the cylinder and projects outwardly of the mill. A pair of electrical position transducers 34, 36 are mounted on the bracket with their longitudinal axes in a radial plane through the centre of the cylinder 28. The transducers are thus on the same side of the cylinder 28 but at different distances therefrom. A further bracket 38 is secured to the chock 22 and projects outwardly of the mill above the bracket 32. A pair of adjustable screws 40, 42 are mounted on the bracket 38 and engage with the movable parts of the transducers 34, 36 respectively.

Vertical displacement of the bearing chock 22 thus causes the bracket 38 and the screws 40, 42 to be displaced vertically thereby varying the electrical outputs e e from the transducers.

I claim:

1. A rolling mill stand comprising a housing and upper and lower roll assemblies, at least one piston and cylinder assembly for displacing one of said roll assemblies relative to the other assembly to vary the gap between the roll assemblies, one component of said piston and cylinder assembly being stationary with the housing and the other component being displaceable with said displaceable roll assembly, a pair of electrical position sensing devices located on the same side of the piston and cylinder assembly but at different distances therefrom and each sensing device having a part stationary with the stationary component of the piston cylinder assembly and a part movable with the movable component, and the electrical outputs of the two sensors being employed to determine the displacement of the central part of the movable component with respect to the stationary component.

2. A rolling mill stand as claimed in claim 1 in which the sensors are positioned outwardly of the mill stand on a common radial line through the axis of the assembly.

3. A rolling mill stand as claimed in claim 2 in which each transducer has its movable part in engagement with a bracket secured to a bearing chock assembly of the lowermost roll of themill and its fixed part secured to a bracket secured to the stationary part of the piston and cylinder assembly.

4. A rolling mill stand as claimed in claim 3 in which the piston-cylinder assembly is located in a housing window of the mill with the piston of the assembly abutting the underside of the bearing chock assembly of the lowermost roll of the mill.

UNITED STATES PATENT OFFICE CERTIFIQATE 0F CORRECHQN PATENT NO. I 3 916 661 DATED I November 4, 1975 INVENT0R(5) I Thomas Walter Hargreaves It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below;

Column 4, line 10, sensors should read -sensing devicesand line 18, "transducer" should read sensing device.

Signed and Scaled this twentieth 3y 0f April1976 [SEAL] A Ites t:

RUTH C. MASON C. MARSHALL DANN Arresting ()fl'icer ('nmmissimrvr nflarenrs and Trademarks 

1. A rolling mill stand comprising a housing and upper and lower roll assemblies, at least one piston and cylinder assembly for displacing one of said roll assemblies relative to the other assembly to vary the gap between the roll assemblies, one component of said piston and cylinder assembly being stationary with the housing and the other component being displaceable with said displaceable roll assembly, a pair of electrical position sensing devices located on the same side of the piston and cylinder assembly but at different distances therefrom and each sensing device having a part stationary with the stationary component of the piston cylinder assembly and a part movable with the movable component, and the electrical outputs of the two sensors being employed to determine the displacement of the central part of the movable component with respect to the stationary component.
 2. A rolling mill stand as claimed in claim 1 in which the sensors are positioned outwardly of the mill stand on a common radial line through the axis of the assembly.
 3. A rolling mill stand as claimed in claim 2 in which each transducer has its movable part in engagement with a bracket secured to a bearing chock assembly of the lowermost roll of the mill and its fixed part secured to a bracket secured to the stationary part of the piston and cylinder assembly.
 4. A rolling mill stand as claimed in claim 3 in which the piston-cylinder assembly is located in a housing window of the mill with the piston of the assembly abutting the underside of the bearing chock assembly of the lowermost roll of the mill. 